Halogenated polyester compositions and process for preparing the same



United States PatentOtfice 3,536,782 Patented Oct. 27, 1970 3,536,782HALOGENATED POLYESTER COMPOSITIONS AND PROCESS FOR PREPARING THE SAMEUlrich Toggweiler and Frank F. Roselli, Redwood City, Calif., assignorsto Diamond Shamrock Corporation, a corporation of Delaware No Drawing.Filed Jan. 25, 1967, Ser. No. 611,574 Int. Cl. C08f 21/02; C08g 17/12US. Cl. 260869 11 Claims ABSTRACT OF THE DISCLOSURE Halogenatedpolyester containing compositions having a high degree of flameresistance are prepared by a method of post halogenation wherein a basepolyester containing non-alpha, beta ethylenic nnsaturation other thanaromatic unsaturation is first prepared and then halogenated, thuseliminating the common use of halogenated intermediate raw materials.The halogenated polyesters may be used directly, such as in coatingcompositions or may be reacted with isocyanate containing compounds toform halogenated polyurethane compositions. When the halogenatedpolyesters also contain alpha beta ethylenic unsaturation as derivedfrom alpha, beta unsaturated polycarboxylic acids and anhydrides, theymay be cross-linked and cured in the conventional manner with vinylsubstituted monomers. The halogen containing compositions prepared bythis process exhibit superior flame retardancy, color characteristicsand physical properties than halogenated polyester containingcompositions prepared by reacting halogen containing constituents.

BACKGROUND OF THE INVENTION Polyester resin compositions have achievedwide commercial utility in that they can be cured alone at low tomoderate temperatures or with various reinforcing materials, such assynthetic and natural reinforcing fibers and strands, e.g., glassfibers, nylon, cotton, sisal, asbestos as well as many other materialsin the form of fabric, mat, yarn and the like to give hard, durable,light weight structural materials. Such polyesters also can be appliedto surfaces by spraying roller coating, dipping, brushing or othersuitable means to give tough, weather resistant thermoset coatings. Thehigh strength properties of these compositions combined with their lightweight and durability make them successful competitors for manyapplications with more conventional structural materials. Further,polyesters can also be used in the preparation of urethane polymerswhich can be employed as coatings or in the form of foam for use asinsulation material.

In spite of the excellent physical properties of such polyester-basedcompositions, they possess a major disadvantage in that they areflammable, thereby limiting the areas of potential use. Severalapproaches have heretofore been suggested to improve the flameresistance of polyester compositions and such methods generally involveincorporating a flame-resistant material or element into the polyestercomposition, either as a reactive or non-reactive additive or as anintegral part of one of the basic raw materials.

An elfective, generally economical, and widely accepted approachinvolves incorporating fire retardant fillers or additives into thecomposition, usually just prior to the final polymerization step. Thesefillers or additives generally include materials such as borates,silicates, antimony oxides, phosphates, phosphites and derivativesthereof. However, when a filler-type component is added it has beenfound that the filler may separate or precipitate during the subsequentcuring process, producing variable fire retardancy, color and lighttransmitting properties in the cured resin. Further, transparent curedarticles usually cannot be produced using fillers because of theiropaque properties. In addition such fillers tend to result in reducedphysical strength and hardness of the polyester composition. Filler-typematerials may tend to migrate to the surface of the resin and undergohydrolysis when they come in contact with moist air resulting in surfacedegradation.

Reactive additive type compounds become part of the cured resin andtherefore cannot migrate or be extracted by water; however, they stillmay have a deleterious effect on the physical properties of thepolyester composition. It has been found that some of the more readilyavailable fire-retardant compounds which are useful for this purpose aresufiiciently stable under mild exposure conditions, but break down uponexposure to weathering or moderate temperature cycling, thereby causingthe polyester composition to lose whatever flame resistance it mighthave had originally. Thus, the costly step of incorporating suchcomponents either of the filleror additive-type in the polyestercomposition may be undertaken without the realization of any permanentbenefit.

Many methods have been proposed to overcome the shortcomings of thefiller and additive type fire proofing components by using halogenatedraw materials in the polyester composition, that is, react either ahalogenated polycarboxylic acid and/or halogenated polyhydric alcohol toobtain a halogen containing fire retardant polyester composition. Forinstance, polyester compositions previously have been prepared byreacting halogenated materials, such as tetrabromophthalic anhydride,2,3-dihalo succinic acid, polyhalogenous epoxides, and 1,4,5,6,7,7-hexachlorobicyclo(2.2.1)-5-heptane-2,3 dicarboxylic anhydride (morecommonly known as chlorendic anhydride) with various glycols, saturatedand unsaturated polycarboxylic acids and anhydrides to producepolyesters of varying degrees of flame retardancy. Even though suchmodified polyesters represent an improvement in the art they do exhibitcertain undesirable properties.

When employing such halogenated raw materials, particularly brominecontaining components, in the preparation of polyester resins, it hasgenerally been found that the temperatures required forpolyesterification are higher than the degradation temperature of thehalogenated component. Thus, during the polyesterification reactionthere is a tendency towards elimination of halogen throughdehydrohalogenation. The contamination of the polyester reaction by thisrelease of hydrogen halide causes the following deleterious sideeffects: (a) product color is degraded; (b) polymer chain scissionoccurs making it impossible to achieve the desired high molecularWeights; (c) attack on unreacted glycols by hydrogen halide causescyclic etherification of the glycols, thus not only wasting costly rawmaterials but generating undesirable compounds; and (d) the presence ofhydrogen halide in the final mixture of polyester base withethylenically unsaturated monomers interferes with the subsequent freeradical initiated cross-linking reactions resulting in undercuredproducts of inferior properties. Such problems can be reduced somewhatby the use of esterification catalysts and long low temperatureprocessing cycles for the esterification reaction. However, longprocessing cycles are costly and additives may themselves producefurther undesirable side reactions such as introducing a permanentcloudiness into the product.

A further problem with utilization of known halogencontaining reactivecomponents, particularly chlorinated compounds, in preparation of fireretardant polyesters lies in the difiiculty of getting enough chlorineinto the polyester to meet the more stringent fire retardantrequirements. For instance, commercially available chlorine containingcomponents suitable for polyester manufacture rarely exceedapproximately 55% chlorine. At that chlorine level it is difficult, ifnot impossible, to attain a level of chlorine in the final monomersolution of chlorinated base polyester to meet many of the more rigidfire retardant requirements without resorting either to additives havingthe aforementioned drawbacks or to use of hard to handle highconcentration, high viscosity resin solutions.

SUMMARY OF THE INVENTION It is, therefore, an object of this inventionto provide novel halogenated fire retardant polyester compositions inwhich the requirement for preparation and/or use of expensivehalogenated intermediates is eliminated.

A further object is to provide means of preparing, through a novelprocess, halogenated fire retardant polyester resins having improvedcolor and fire retardant properties.

It has now been discovered that polyester resins can be halogenateddirectly, i.e., after the polyesterification reaction has taken place.In this manner the color degrading step and also the necessity ofpreparing or utilizing an expensive halogenated intermediate can bebypassed completely by first preparing polyester from readily availableinexpensive raw materials by conventional means in conventionalequipment and then halogenating the polyester at temperatures much belowthe degradation temperature.

The halogenated polyester base, depending on formulation and intendedend use, may then be dissolved in a variety of ethylenically unsaturatedmonomers. These mixtures may be cross-linked by well known free radicalmechanisms with conventional peroxide catalysts, pro moters,accelerators, etc., to prepare a large variety of cured articles havingexcellent color, desirable physical characteristics, and highly fireretardant properties. Carboxyl rich post-halogenated polyesters may beformulated by Well known techniques into Water soluble coatings,binders, and the like.

Alternatively, hydroxyl rich polyester bases halogenated by the processof this invention may be formulated with various polyisocyanates toprepare fire retardant polyurethane and polyurea foams, coatings, andthe like.

The polyester base resin composition which is to be halogenated may varyin composition depending upon Whether the polyester base resin is to beused in the preparation of a cross-linked polyester or a urethanepolymer. Generally, the polyester base resin is prepared by reacting anorganic dicarboxylic acid, acid anhydride or mixtures thereof(hereinafter referred to as dicarboxylic acid compound) with one or morepolyhydric alcohols. In the preparation of cross-linked polyesters it isnecessary in order to effect subsequent cross-linking that the polyesterbase resin contain an ethylenic unsaturation other than aromaticunsaturation to provide polymerization sites for cross-linking with thecross-linking agent. Thus, when the polyester base resin is to be usedfor preparing cross-linked polyesters, it is necessary that thepolyester base resin contain at least one alpha, beta-ethylenicallyunsaturated dibasic acid or anhydride thereof in order for the polyesterto react subsequently with the cross-linking agent to form toughinfusible polymers.

Urethane polymers are prepared by reacting a compound containing atleast two active hydrogen atoms per molecule with a polyisocyanate. Thetwo active hydrogen atoms per molecule generally are provided byhydroxyl groups. Thus, if the polyester is to be used in the preparationof urethane polymers, the polyhydric alcohol is used in excess of thedicarboxylic acid to ensure that a sufficient number of reactive sitesare available for subsequent reaction with the polyisocyanate. Since theprincipal reaction in preparing urethane polymers is between thehydroxyl groups of the polyester and the isocyanate groups of thepolyisocyanate, there is no need to have present in the polyester baseresin alpha, beta-ethylenic unsaturation which is capable of subsequentvinyl copolymerization. However, since the polyester base resins of thisinvention are to be halogenated prior to either cross-linking with acopolymerizable monomer or reaction with a polyisocyanate to form aurethane polymer said polyester must be readily susceptible to partialhalo genation to provide a polyester base resin after halogenation witha halogen content ranging from about 10% up to about 60%, by weight,preferably about 20% up to about 40%, by weight halogen based on theweight of the polyester base resin without affecting the active sites ofthe polyester base resin, i.e., either alpha,beta-ethylenic unsaturationnecessary for subsequent cross-linking with a cross-linking agent or theactive hydrogen atoms on the hydroxyl groups which react with theisocyanate groups of the polyisocyanate.

An unexpected discovery of the present invention is the finding thatwhen halogenating a polyester base resin composition prepared from adicarboxylic acid compound comprising a mixture of analpha,beta-ethylenically unsaturated dicarboxylic acid or acid anhydridethereof and an ethylenically unsaturated dicarboxylic acid or anhydridethereof free of any alpha,beta-ethylenic unsaturation, other thanaromatic unsaturation, that the halogen preferentially adds to thenon-alpha,beta-ethylenic unsaturation prior to adding to thealpha,beta-unsaturation linkage, thereby leaving these latter potentialpolymerization sites available for subsequent polymerization with thecross-linking agent. Thus, the amount of halogen which is desired to beadded is controlled by the amount of non-alpha,beta-ethylenicunsaturation present, other than aromatic unsaturation.

Specifically, it has been unexpectedly found that a polyester base resinprepared by reacting a polyhydric alcohol with a mixture ofethylenically unsaturated dicarboxylic acids or acid anhydrides thereofcontaining alpha,betaethylenic unsaturation, for instance maleic acid,with a non-alpha,beta-ethylenically unsaturated dicarboxylic acid oracid anhydride thereof, such as tetrahydrophthalic acid, may behalogenated, so that the halogen addition to the polyester base resin ispreferential to the non-alpha,betaethylenically unsaturated acid, toalmost the total exclusion of halogen addition to thealpha-beta-ethylenically unsaturated acid. The preferential addition ofhalogen to the non-alpha,beta-ethylenically unsaturated dibasic acids tothat of alpha-beta-ethylenically unsaturated acids is not fullyunderstood, but it is believed that the proximity of the carboxy groupsto the ethylenic unsaturation hinders the addition of a halogen atom tothe alpha,beta-ethylenic unsaturated bond, whereas the halogenation ofthe dicarboxylic acids having non-alpha,beta-ethylenic unsaturationproceeds at a much faster rate. For instance, it has been found that apolyester prepared by reacting ethylene glycol, tetrahydrophthalic acidand maleic acid is halogenated preferentially through the addition ofthe halogen atoms to the unsaturated bonds of the tetrahydrophthalicacid moiety at a rate of approximately ten times faster than the rate ofhalogen addition to the unsaturation bonds of the maleic acid moiety.Accordingly, if the polyester base resin composition is to be used inthe preparation of cross-linked polyesters, the dicarboxylic acidcompound employed is preferably a mixture of an alpha,beta-ethylenicallyunsaturated dicarboxy acid or acid anhydride thereof and anethylenically unsaturated acid or acid anhydride thereof free fromalpha,betaethylenic unsaturation other than aromatic unsaturation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In preparing the halogenatedpolyester base resin for use in the preparation of either cross-linkedpolyesters or urethane polymers, non-alpha,beta-unsaturated dicarboxylicacids and acid anhydrides thereof, while being preferred, need not beemployed so long as the polyester base resin composition is susceptibleto halogenation without deleteriously affecting either thealpha,betaethylenic unsaturation required for subsequent cross-linkingor the active hydrogen atoms for subsequent reaction with the isocyanategroups of the polyisocyanates in the preparation of the urethanepolymers. For instance, the halogen receptive sites may be provided byunsaturated polyhydroxyl compounds or by other means wherein thehalogenation rate of said halogen receptive sites is at least severaltimes more rapid than the rate for the alpha,betaethylenic unsaturationpresent.

Alpha,beta-ethylenically unsaturated carboxylic acids and anhydridesthereof suitable for use in preparing the products of this invention areexemplified by maleic, fumaric, itaconic, citraconic, mesaconic and thelike containing up to about 20 carbon atoms per molecule. Unsaturatedcarboxylic acids and anhydrides free from any alpha,beta-ethylenicunsaturation other than aromatic unsaturation which may be present inthe polyester as a halogen acceptor are represented by compounds such asendo-bicyclo (2.2.2) octa--ene-2,3-dicarboxylic; tetrahydrophthalic;

endo-cis-bicyclo(2.2.1 -5-heptene-2,3-dicarboxylic; 3,6-endoxo-l,2,3,6-tetrahydrophthalic; methyl-5-norborene-2,3-dicarboxylic;

l-decenyl succinic;

acetylene dicarboxylic and the like containing up to about carbon atomsper molecule. When the polyesters are prepared for subsequentcross-linking with unsaturated monomers these acids and anhydrides arecharacterized by having a halogenation rate faster than thealpha,beta-ethylenically unsaturated compounds employed.

Also, other dicarboxylic acids and anhydrides may be employed to modifythe physical properties of the final polyester product, provided suchcompounds do not participate in either the halogenation or subsequentcrosslinking reactions. Such materials are saturated or contain aromaticunsaturation but are free from any ethylenic aliphatic unsaturation andare not susceptible to halogenation under the conditions employed. Theseacids and anhydrides may be substituted with halogen, if desired.Typical of this group of modifying acids and anhydrides are:orthophthalic, isophthalic, terephthalic, adipic, azelaic, diglycolic,trimellitic, pyromellitic, diphenic, cyclohexane dicarboxylic,dichlorosuccinic, tetrachlorophthalic, glutaric, naphthalic and the likecontaining up to about 20 carbon atoms per molecule.

A wide variety of polyhydroxy compounds are suitable for preparing thebase polyesters and may either by satu-,

rated or may contain active unsaturation which may be susceptible tosubsequent halogenation thus providing additional means of increasingthe halogen content of the final product. It is preferable that suchunsaturation, however, be either relatively immune to halogenation,i.e., aromatic, or in the case of polyesters intended for subsequentvinyl cross-linking, be readily halogenated, i.e., have a halogenationrate at least faster than the halogenation rate of thealpha,beta-ethylenically unsaturated dicarboxylic acid compound. Thepolyols which may be employed generally contain from about 2 to 24carbon atoms. Specific polyols are illustrated by the following:ethylene glycol, diethylene glycol, propylene glycol, butane diol,butene diol, hexane diol, hexene diol, butyne diol, cyclohexane diol,cyclohexene diol, neopentyl glycol, hydrogenated bisphenol A, adducts ofcyclopentadiene and unsaturated polyhydroxy compounds, polyethyleneglycol, 2,2,4-trimethyl-1,3-pentane diol, cyclohexane dimethanol,trimethylol ethane, trimethylol propane, pentaerythritol, dichlorobutanediol, 3-chloro-l,2-propane diol, alkylene oxide adducts of variousbisphenols, allyl ethers of polyhydroxyl compounds, such as glycerylalpha allyl ether, diallyl ether of pentaerythritol, allyl ethers oftrimethylol pentane. If the polyester base resin composition is to beused in the preparation of urethane polymer, at least one of thereactants must contain active unsaturation. Accordingly, polyhydroxycompounds containing active unsaturation, such as the foregoingethylenically unsaturated polyhydric alcohols, may be reacted withdicarboxylic acids and anhydrides which are saturated or containaromatic unsaturation but are free of any ethylenic unsaturation aspreviously mentioned.

In preparing the polyester base resin composition which is to be usedeither in the preparation of a crosslinked polyester of the preparationof urethane polymer, typical esterification reaction conditions may beemployed, the only variation being the concentrations of thedicarboxylic acid compound and polyhydric alcohol employed. When thepolyester base resin composition is to be used for preparingcross-linked polyesters the polyhydric alcohol is charged to theesterification reaction zone in an amount sufficient to reacttheoretically with all of the carboxyl groups present in the reactionzone. Generally, however, more than the theoretical amount of thepolyhydric alcohol necessary to react with all of the carboxyl groups isemployed and the amount of excess alcohol is determined by the reactionconditions, the particular dicarboxylic acid compound charged and theproperties desired in the resin product. Usually the amount ofpolyhydric alcohol is not more than about 125 mol percent, preferablywithin the range of about to mol percent of the theoretical amountnecessary to react with all of the carboxylic groups present therein. Itshould be mentioned, however, that for certain end uses, such as watersoluble binders and coatings, an excess of car? boxyl may be employed.

The ratios of the various dicarboxylic acids or anhydrides to be usedmay vary widely according to the properites desired in the finalcross-linked product. Amounts of the non-alpha,beta-ethylenicallyunsaturated component should be suificient to result in a halogenatedpolyester base having a halogen content of between about 10% and 50%,preferably about 20% to 40% by weight. In addition, there must bepresent sufi'icient cross-linking capability in the form ofalpha,beta-ethylenic unsaturation to ensure adequate physical propertiesof the final cross-linked polymer. Thus, the proportion of alpha,betaethylenically unsaturated component present in the polyester should beat least about 15 mol percent and preferably in the range of about 33 to67 mol percent. Too low active unsaturation will result in inadequatecrosslink density and heat distortion temperature in the final curedproduct resulting in impaired fire retardant properties.

In preparing polyester base resin compositions which are to beeventually used in the preparation of urethane polymers, the resultingpolyester base resin should contain at least two active hydrogen atomsper molecule and, accordingly, the polyhydric alcohol is used in amountssubstantially in excess of that theoretically necessary to react withall of the carboxyl groups present therein. The amount of molar excessof hydroxy to be employed will depend upon the functionality of thepolyhydric alcohol, the desired excess hydroxyl equivalency and theintended end use of the specific product. In general, however, the ratioof hydroxyl equivalent employed per carboxyl equivalents employed percarboxyl equivalent will range from about 1.2 to4.0.

With either type of base resin the polyhydric alcohol is usually chargedto the reaction vessel first followed by the polycarboxylic acids oranhydrides. The acids may be added in a single charge or reacted insuccessive stages to alter the end properties of the polymer if desired.Usually the polyesterification may be accomplished simply by heating thereaction mixture at temperatures of about 150 to 250 0., preferably atapproximately 180 to 220 C. With certain difiicult to react rawmaterials it may be practical to add certain known esterificationcatalysts such as paratoluene sulfonic acid or metalorganic salts, suchas dibutyl tin oxide or stannous oxalate, to speed the reaction but thisstep is usually not necessary. Chain stopping agents are sometimes addedin minor proportions to terminate the growth of the polyester chain byintroducing terminal hydrocarbon residues. Among such compounds aremonohydric alcohols, e.g., butyl, octyl, tetrahydrofurfuryl, dichloro ordibromopropanol and the like or monobasic acids such as propionic,chloroacetic, benzoic, etc. An inert gas such as nitrogen or carbondioxide is usually passed through the mixture to eliminate sidereactions which could lead to gel formation or color degradation. Thereaction generally proceeds easily and smoothly and the rate of reactionis primarily governed by the capacity of the equipment selected toremove the water of esterification which results from the directesterification. The reaction is usually carried out at atmosphericpressure, but vacuum distillation has been found to be an acceptablemeans of removing the water of esterification.

Completion of the esterification reaction may be observed in a varietyof ways well known to those skilled in polyester technology. One suchprocedure which may be employed is to compare the proportion of waterwhich is removed to the theoretical amount. Other methods frequentlyemployed involve dissolving a cooled sample of the product in a suitablesolvent medium such as styrene to observe its degree of polymerizationas evidenced by relative viscosity, acid number or melting point andusing such data as a guide to indicate the completion of the reaction.Preferably, the polyester base resin composition of the presentinvention that is to be used in the preparation of cross-linkedpolyesters is characterized by an acid number of less than 50 (mg. ofKOH per g. resin), a molecular Weight of greater than 1000 and a colorof less than 400 as determined by the method of the American PublicHealth Association (APHA). Such base resins vary from viscous liquids tobrittle solids depending upon the particular raw materials employed.

The polyester base resin composition is then halogenated to obtain ahalogenated polyester base resin composition containing approximately to60%, preferably 20 to 40%, by weight halogen in the polyester base resincomposition. Halogenation of the polyester base resin compositiongenerally is achieved employing standard halogenation procedures andreaction conditions. For instance, the polyester base resin compositionis first dissolved in a solvent which is not readily susceptible tohalogenation, such as for example, the lower molecular weighthalogenation saturated hydrocarbons, e.g., methylene chloride,chloroform, chlorofluoromethane, ethyl ene dichloride, trichloroethane,and the like; carbon disulfide; acetic acid; diethyl ether; and thelike. The halogenation reaction can be conducted at temperatures rangingfrom a low of about 50 up to about 50 C., preferably 2S to 40 C. Hightemperatures lead to side reactions which impair performance and colorof the final product.

As mentioned, the preferred embodiment of the present inventioncomprises a polyester base resin composition containing, afterhalogenation, approximately 10 to 60% by weight halogen. The halogen maybe added to the solution of polyester base resin composition either as aliquid or gas. For instance, bromine or chlorine may be added to thesolution of polyester base resin beneath the surface of the solutioneither by gravity feed or low pressure blow case. The addition of thehalogen is carried out slowly and at moderate temperatures to avoid sidereactions. Preferably, the amount of halogen to be added is firstdetermined either by titration or by calculation based on the non-alpha,beta-ethylenic unsaturation, other than aromatic unsaturation, presentin the 'base resin and then the halogen is added to the base resin lessapproximately 1% to 1.5% in order to avoid end point problems. Since thehalogenation of this invention is an addition type reaction producingonly traces of hydrogen halide byproducts it is usually not necessary toemploy activators or free radical initiators such as peroxides orpersulfates. The reaction generally proceeds smoothly and evenly to theend point at atmospheric pressure.

The solvents may be removed either by vacuum distillation, or evaporated.at atmospheric pressure with the aid of an inert gas sparge andrecovered for reuse. The temperature at which the solvent is removedshould not exceed approximately 180 C. in order to prevent decompositionof the halogenated polyester base resin. Accordingly, the solvent shouldbe removed at temperatures of less than 180 C., preferably in the rangeof approximately to C. The halogenated base resins of this inventionrange from viscous liquids to brittle solids depending upon initialformulation. These resins have excellent clarity and a color ratingbelow 400 APHA even when bromine is the halogen.

The halogenated base resins may be either stored for future use orformulated by techniques well known to those skilled in the art intofire retardant products suitable for molding, laminating, casting,coating, foam, and other applications. In preparing cross-linkedpolyesters, the halogenated base resins are mixed with monomers capableof copolymerization with the alpha, alpha-ethylenic unsaturation presentin the base resin. This dissolution may be carried out in the cold orthe hot base resin available immediately after completion of the solventstripping step may be added directly to the monomer in a manner similarto common practice in standard polyester production. Suitablecross-linking agents are polymerizable ethylenically unsaturatedmonomers having the CH =C grouping and are exemplified by styrene, vinyltoluene, alpha-methyl styrene, chlorostyrene, fluorostyrene',trifluoromethylstyrene, divinylbenzene, di allyl phthalate, triallylisocyanurate, the alkyl acrylates, the lower alkyl and alkenyl esters ofmaleic and furnaric acid, vinyl pyridine, vinyl pyrollidone, vinylcarbazole, vinyl ethers, vinyl ketones, and the like. Because of itsfavorable cost, compatability and reactivity as well as excellentphysical properties it provides in the final crosslinked polyesterproduct, styrene is the preferred crosslinking agent. The proportion ofcopolymerization monomer to unsaturated polyester may be varied betweenapproximately 20% to 60%, preferably about 25% to 50%, by weight of themonomer based on the weight of the polyester.

Polymerization inhibitors usually on the order of 0.001% to 0.1% byweight based on the base resin/ monomer mixture may be used to preventpremature polymerization or curing of the mixture and to moderate thegel and cure after addition of catalysts. Exemplary of such inhibitorsare hydroquinone, benzoquinone, p-(tertiary butyl)-catechol, and thelike. Polymerization catalysts also are added to the mixture ofunsaturated polyester and cross-linking agent at the time of use toelfect polymerization or curing. Usually employed are the freeradical-forming catalysts and include peroxides, for example, acetyl,benzoyl and dicumyl peroxide; hydroperoxides such as cumenehydroperoxide; peresters such as tertiary butyl perbenzoate and tertiarybutyl-peroctoate; azo compounds such as alpha,alpha'-azo-diisobutyronitrile; ketone peroxides such as methyl ethylketone peroxides. Additionally, activators or accelerators such ascobalt, naphthenate, alkyl mercaptans, dialkyl aromatic amines, and thelike may be used to promote the crosslinking reactions so that thepolymerization orcure can be effected at lower temperatures or shorterreaction times. The polymerization conditions for effecting thecross-linking reaction may be selected from a wide variety of techniqueswell known in the art. The temperature employed depends on a variety offactors including the type of end product to be made, the boiling pointof the cross-linking agent, catalyst activation temperature, andexothermic characteristics of the polymerization mixture.

While the products of this invention have excellent flame retardantproperties and good color for most applications minor improvements canbe made to meet the most stringent requirements by use of certainadditives. These additives are used in such minor proportions so thatthe physical properties of the cured polymers are not seriouslyaffected. It has been found, for instance, that the addition of smallamounts, e.g., 1% to 10%, of certain pentavalent phosphorous compoundsto the halogenated base resin monomer m'nt not only improves color butenhances flame retardance as well. Exemplary of such pentavalentphosphorous compounds which have been found satisfactory include themono, dior trialkyl or alkylene phosphates wherein each of the alkylgroups contain from about 1 to about 4 carbon atoms, for instance,methyl-, ethyl-, propyl-, allyland butylisomers thereof. Certain epoxidecompounds, for instance epichloroor epibromohydrin have also been foundto improve color when used in amounts less than 5%, preferably less than1%.

The resultant halogenated polyesters may be used to manufacture a widevariety of useful end products which are characterized by a high orderof non-flammability and weathering resistance. Certain of theformulations also possess excellent chemical resistance while retainingfire retardancy. Examples of flame retardant products which may bemanufactured with the halogenated resins of this invention are:translucent building panels; molded trays, lbaskets, etc.; electricalparts; truck and car bodies, boats, chemical resistant process equipmentand many others.

While the preferred aspect of the present invention is preparinghalogenated cross-linked polyesters, another utility of the halogenatedpolyester base resin composition is the preparation of urethanepolymers. As mentioned above, the formation of urethane polymers isachieved by reacting a polyisocyanate, usually a diisocyanate of thearomatic type, with a compound containing at least two reactive hydrogenatoms per molecule, generally, the reactive hydrogen being the hydrogenof a hydroxyl group. Polyurethanes are usually prepared in the form offoams because that form has achieved wide commercial acceptance. Theymay be prepared by reacting the halogenated polyester base resincomposition with the polyisocyanate in the presence of Water, whichreacts with a portion of the isocyanate to form carbon dioxide which inturn acts as a blowing or expanding agent to enable a foamed product tobe formed. Alternatively, liquid blowing agents such as the halogensubstituted lower molecular weight alkanes, e.g.,trichlorofluoromethane, dichlorodifluoromethane,dichlorotetrafluoroethane, trichlorotrifluoroethane and the like, havefound wide acceptance and may be employed in amounts ranging from about2% to 40%, by weight of the total weight of the urethane foamingmaterials. The halogenated polyester base resin compositions andpolyisocyanate are employed in amounts necessary to achieve the desiredchain extension, cross-linking network formation and the like. Foamsprepared according to the present invention, may have, if desired,residual unreacted hydroxy and/or isocyanate radicals. In general,however, one equivalent of hydroxyl contained in the halogenatedpolyester base resin 10 composition is used with about one equivalent ofthe polyisocyante.

The relative rigidity or flexibility of the urethane foams produced maybe at least partially controlled by the composition of the halogenatedbase polyester as well as the type of polyisocyanate employed.Flexibility is controlled by both the chain length and functionality ofpolyester reactants and the amount of excess hydroxyl employed. Forinstance, relatively more flexible foams are obtained when employinglong chain diols in the base polyester formula prior to halogenation,with the more rigid types resulting from use of the more highlyfunctional shorter chain triols and tetraols.

The polyisocyanates which may be employed have two or more reactiveisocyanate groups as exemplified by hexamethylene diisocyanate,tolylene2,4-diisocyanate, tolylene-2,6-diisocyanate, diphenylmethanediisocyanate, p,p'- meta-phenylene diisocyanate, polymethylene phenylenepolyisocyanates, bis(toluene)-diisocyanate, the naphthylenetriisocyanates, and mixtures thereof.

In formulating the halogenated polyester base resins into foamingcompositions because of their highly viscous nature it is generallypreferred to use the prepolymer technique wherein the halogenated baseresin is reacted under controlled conditions with an excess ofpolyisocyanate to form relatively low viscosity isocyanate richprepolymer.

To form the final foam the prepolymer is then mixed with an additionalamount of the halogenated base. Because of the usually highly viscous orsemisolid characteristics of the polyester base it is advantageous toreduce viscosity with a minor portion of low viscosity diol or polyolprior to combining with the prepolymer. It is feasible, however, toutilize the halogenated polyester base resins in the preparation ofurethane foams in the molten state at elevated temperatures. In thiscase the molten polyester is pumped at a controlled rate through thenozzle of a foaming machine where it is contacted with and intimatelymixed with a stream of polyisocyanate or isocyanate rich prepolymer.From the nozzle the mixture is delivered to a suitable mold or cavityfor foam rise and cure. I

In formulating foams there may be employed, in addition to the basicreactants and blowing agents, catalysts such as tertiary amines,tertiary amino alcohols, tertiary ester amines, and the like to speedthe reaction. Other compounding ingredients which may also be employedin the preparation of the urethane polymers include wetting agents andemulsifiers to control foam cell structure, carbon black, titaniumdioxide, mica, wood pulp, silica, and other pigments and fillers, dyes,fungicides, antioxidants, light stabilizers, and the like.

The foamed urethane products prepared employing the halogenatedpolyester base resin composition may have densities from about /2 up toabout 60 pounds per cubic foot, or higher, with an especially preferredfoam product having densities of about 1 to 5 pounds per cubic foot.Depending upon the particular method of blowing, the amounts ofingredients, the type of mold, and the like, the foamed polyurethaneproducts may be open or closed cell. The foam products exhibit good cellstructure, excellent flame resistance and are free from discolorationand crevicing (large, hollow, irregular fissures or voids in the body ofthe foam). These foam products are useful as insulation material forrefrigerators; crash pads in automobiles; potting compounding; heat andsound insulating bats; mattresses; pillows; seat cushions; door panels;insulated booths; life preservers and rafts; sponges; scouring pads; andunderlays for carpets; and in honeycomb laminates for buildingconstruction, airplane construction, and hulls and bulkheads of ships.

In the evaluation and comparison of cross-linked polyester products forflame retardant properties there are a myriad of tests which may beperformed from laboratory through production scale. The most importantof these from the standpoint of commercial acceptance are de- 1 lscribed below in order of increasing severity and are referred tothroughout the ensuing examples. All of these tests are usually carriedout using fiberglass reinforced laminates.

ASTM D635 (American Society for Testing Materials, Pittsburgh,Pennsylvania) A /2 inch Wide by 5 inch long by A inch thick fiberglassreinforced laminate specimen is clamped from one end lengthwise in ahorizontal position so that the /2 inch plane is at an angle of 45 fromhorizontal. An oxidizing flame from a Bunsen type burner is applied tothe free end of the specimen for 30 seconds and then removed. If theflame extinguishes on removal of the flame the specimen is rated asself-extinguishing. If the flame continues to burn after removal of theburner the time required to reach the 4-inch mark is noted and theburning rate reported in inches per minute. This is a rather mild testwhich generally cannot distinguish between the more fire resistantmaterials, but is useful for moderately fire resistant products.

ASTM D757 (Glo'bar test) In this test the end of a similar 5 x /2 x 43inch specimen is contacted with an electrically heated (950 C.) highresistance carbon rod (Globar) and observations are made regardingignition time, burning times and the extent of burning along thespecimen. The results of this test are expressed in inches of burningper minute. The Globar test is more severe than the ASTM D635 test andis suitable for moderately fire retardant specimens which areselfextinguishing in the D635 test. This test lacks sensitivity whenhighly flame retardant materials are encountered. When flame spreadvalues drop below about 0.1 inches per minute it is rarely possible todistinguish between degree of fire retardancy.

Underwriters bench test This test has been established by UnderwritersLaboratories, Inc., Chicago, Illinois as a laboratory screening testsupplementing the diflicult to perform ASTM E-84 Tunnel Test. In thistest a 2-inch wide by 12-inch lOng by -inch thick fiberglass reinforcedspecimen is suspended in a vertical position protected from air draft. A1350* F. oxidizing flame from a Bunsen-type burner is applied to thebottom center of the specimen for 30 seconds and removed. The timerequired for the flame to extinguish after removal of the burner isnoted.

HLT-15 Test The HLT-15 Test is described in the proceedings of TheSociety of the Plastics Industry, Inc., 17th Annual Technical andManagement Conference, Reinforced Plastics Division, February, 1962.

In this test a /2-inch wide by 8-inch long by Az-inch thick fiberglassreinforced specimen is suspended vertically. An oxidizing flame from aBunsen-type burner is applied to the bottom of the specimen in fiveseparate applications of increasing on and off time. After eachsuccessive application the time required for the flame to extinguishafter removal of the burner is observed. The specimen passes each stageif the flame extinguishers before the next scheduled application offlame. Successful passage of each stage of the test is worth 20 pointsto a total of 100. This test is able to distinguish between highly fireretardant materials which would give very high flame resistanceaccording to ASTM D635, D757 and the UL Bencih Test, previouslydescribed.

Military test standard No. LP406-Method No. 2023.2 (Bureau of ShipsTest) In this test a Az-inch by /2-inoh by 5-inch long specimen issuspended inside of an electrically heated coil so that the specimendoes not touch the coil. The coil is heated with precisely controlledpower supply to repetitively uniform high temperature and flame ignitionis started by means of a continuous spark immediately above the heatzone. The time required for the specimen to ignite and the time toextinguish after cessation of heating is recorded. This test is a verysevere test for fire resistance and is suitable for measuring relativediflerences between highly fire resistant products but is not directlycorrelatable to other tests involving direct flame.

ASTM E-84Tunnel test This test is employed to establish the relativefire resistance of commercial building materials. Specimens having atotal measurement of 25 feet by 20 inches are sealed in a 25-foot longtest chamber (tunnel) and ignited at one end by a continuous controlledgas flame. The flame front advance along the specimen during a giventime is measured and flame spread ratings are calculated based on anindex of zero for asbestos and for red oak. This test is closely relatedto actual fire conditions and therefore is generally accepted inindustry as a standard.

In order that those skilled in the art may more cornpletely understandthe present invention and the preferred methods by which the same may becarried into effect, the following specific examples are offered.

EXAMPLE 1 (a) Preparation of base polyester A four liter resin kettleequipped with thermometer, stirrer, inert gas sparge tube, heated refluxcolumn, and total condenser is charged with 1445 g. (23.3 mols) ofethylene glycol, 1680 g. (11.1 mols) of tetnahydrophthalic anhydride (4cyclohexene 1,2 dicarboxylic anhydride) and 0.21 g. of hydroquinoneinhibitor.

A nitrogen sparge is started and the temperature is raised to C. atwhich point a mild exotherm to C. takes place. The temperature ismaintained at 150 C. for about 1.5 hours after which 1085 g. maleicanhydride (11.1 mols) are added and the temperature raised over a fourhour period to 200 C.

The temperature is maintained at 200 C. for an additional six hoursduring which time the water of condensation is removed through theheated reflux column and total condenser in a manner so that allrefluxing glycol is returned to the reactor. At the end of the reactionperiod the reaction product is transferred to a separate vessel andallowed to cool at room temperature to a somewhat tacky solid. 98.5% ofthe theoretical water of condensation is collected during the reactionand the yield of base polyester is 90.6% of the initial charge.

The acid value of the product is 33.5 (milligrams of potassium hydroxideper gram of resin). The viscosity of a clear, substantially colorlesssolution of the base polyester at a concentration of 70% by weight instyrene is 12 stokes as determined by the standard Gardner-Holdt bubbleviscometer at 25 C.

(b) Halogenation of base polyester A four liter glass reactor equippedwith thermometer, stirrer, inert gas sparge tube, and reflux condenseris charged with 2000 g. of methylene chloride followed by 1835 g. of thebase polyester resin prepared in (a) above. The base resin dissolveseasily in the solvent with moderate stirring to form a clear solutionhaving a viscosity of less than one poise. The reaction vessel is thenequipped with a graduated, pressure equilibrated addition funnel havingan extended outlet reaching below the surface of the polyester solution.Through this device 835 g. (5.2 mols) of liquid bromine are added to thewell stirred nitrogen sparged solution at temperatures between 18 C. and22 C. during about a 2% hour period. Throughout this period the brominecolor dissipates immediately on contact with the reaction mixtureindicating near instantaneous reaction. The amount of bromine added isequivalent to the unsaturation present in the tetrahydrophthalicanhydride moiety less about 2%.

The resulting solution of brominated polyester is only slightly darkerin color than before bromination and has a viscosity of less than onepoise. The reflux column is replaced by a total condenser and themethylene chloride is completely removed by heating the mixture to 150to 160 C. under a mild nitrogen sparge. The last traces of solvent areremoved by application of a vacuum of 50 to 100 mm. of mercury for to 20minutes. At the end of this period the molten brominated base resin istransferred to a separate vessel and allowed to cool to roomtemperature. Only trace amounts of hydrogen bro mide are detected in therecovered solvent. The cooled brominated polyester is a very lightyellow brittle solid having an acid value of 21.5 and a viscosity, asmeasured at 70% concentration in styrene at 25 C., of nine stokes. Thecombined bromine content as found by analysis is 31.5% compared to thetheoretical 31.3%. The styrene solution has a color of less than 400 onthe APHA scale. The addition of either about 3% of trimethylphosphate orabout 0.5% epichlorohydrin to this mixture reduced the color to lessthan 200 on the APHA scale.

(c) Evaluation To a well stirred solution of 0.066 g. of hydroquinone in342 g. of styrene at 70 C. are added 658 g. of the brominated basepolyester prepared in (b) above, to form a solution having a viscosityof approximately 4.5 stokes at 25 C. The resulting brominated polyestersolution, containing approximately 20.7% bromine, on addition of 1% byweight of tert-butyl peroctoate is converted to a hard, tough insolublecross-linked product at 180 F.'in a short period of time.

To evaluate fire retardant properties of the brominated polyesterstyrene mixture, A" thick glass reinforced laminated are prepared fromtwo layers of 2 oz. per square foot fiberglass mat and the resincatalyzed with 1% tert-butyl peroctoate. After curing 3 hours at 180 F.the laminates are tested according to the Globar Test (ASTM D757) andare found to have a burning rate of about 0.14 inch per minute.

Similar laminates, A thick, prepared with a single layer of glass mathave a burning time of less than three seconds when tested according tothe U. L. Bench Test. Specimens taken from the same laminate arenon-burning according to the ASTM D635 test.

Using a single layer of 2 /2 oz. per square foot glass mat a 0.055 inchthick laminate is applied to one side of several inch thick plywoodboards 20 inches in width and totaling 25 feet in length. Roomtemperature cure is achieved using 0.015% cobalt octoate and 1% methylethyl ketone peroxide added to the brominated polyester solution. After24 hours post-cure at 140 F. good Barcol surface hardness of 40 to 50 isobtained. (Barcol Tmpressor model 934-1 manufactured by the BarberColman Company.)

When tested by the standard Tunnel test (ASTM E-84) this panel has aflame spread rating of 77, illustrating the excellent flame retardingability of even thin layers of the brominated polyester. Plywood withoutthe coating consistently gives flame spread ratings under the sameconditions in the 200 to 400 range.

EXAMPLE 2 (a) Preparation of polyester 1548 pounds of ethylene glycoland 1800 pounds of tetrahydrophthalic anhydride are charged to a 500gallon stainless steel reaction vessel equipped with agitator, heatingcontrols and partial reflux condenser. 204 grams of hydroquinone areadded and the mixture heated to 155 C. and maintained at thattemperature for 1% hours. At that time 1150 pounds of maleic anhydrideare added and heating is continued to 195 to 200 C. and maintained atthat temperature for about 10 hours. During the reaction period thewater of condensation is continuously removed through the partialcondenser with the aid of a carbon dioxide sparge. The polyester baseresin is then transferred to separate vessels and allowed to cool toambient temperature.

The cooled polyester has a final acid value of 36 and on dissolution toa 70% concentration in styrene forms a clear solution having a viscosityof approximately 13 stokes and a color of approximately on the APHAstandard. The resin yield is 4,074 pounds.

(b) Bromination of polyester 1865 grams of this polyester base resin aredissolved in 1865 grams of methylene chloride in a glass reactorequipped for bromination as in Example 1. 847 grams of bromine are addedover a four hour period at 13 to 18 C. The resulting solution is clear,has a viscosity of 0.75 poise and a specific gravity of 1.525. Solventdistillation is carried out at atmospheric pressure with the aid of aninert gas sparge up to a temperature of 175 C. over a 4 hour period.Approximately 0.2% HBr is found in the recovered solvent. On cooling,the brominated polyester is a pale yellow brittle solid having a brominecontent of approximately 31.5%, a viscosity of about 5 stokes whendissolved to a concentration of about 68% in styrene. The styrenesolution has a color of approximately 400 on the APHA standard.

A mixture of 68.5% brominated polyester base resin, 31.0% styrene and0.5% epichlorohydrin had a bromine content of about 21.6%, a viscosityof about 5 stokes at 25 C. and a color of approximately 175 on the APHAstandard. Laminates prepared from this solution, as in Example 1, have aburning time according to the U. L. Bench test of less than 5 seconds.

The above polyester solution is catalyzed with 1% benzoyl peroxide andused to prepare a /2 inch thick laminate with 40 plies of glass cloth.After curing at 100 C. for 24 hours, specimens from the laminate aresubjected to the Bureau of Ships Test (Federal Test Standard 406TestMethod 2023) with results of: Ignition time 75 seconds, extinguishingtime 82 seconds. Results of 55 seconds minimum and seconds maximumrespectively, are usually considered passing.

EXAMPLE 3 187 pounds of the polyester base of Example 2 are dissolved in187 pounds of methylene chloride and transferred to a 50 gallonglass-lined vessel equipped with agitator, reflux and total condensers,receiver, inert gas sparge, and means of adding liquid bromine below thesurface of the reaction mixture. 85 pounds of liquid bromine are addedcontninuously over a 5% hour period while the reaction temperature ismaintained at 16 to 28 C. with cooling. After completion of thebromination the methylene chloride is distilled out by application ofheat to C. A carbon dioxide sparge is maintained during the distillationwith a vacuum of bout 26 inches of mercury applied during the last hourof the six hour stripping cycle- A pale yellow molten brominatedpolyester which is recovered is transferred to a separate vessel and'allowed to cool to a hard brittle solid having a bromine content ofabout 31.3%.

The following three copolymerizable mixtures are prepared from thisbase.

67 parts of the brominated polyester resin are dissolved in 33 parts ofstyrene containing 0.0067 part of hydroquinone. To this mixture areadded 0.5 part of epichloro- 'hydrin, 0.03 part of zinc octasol, 0.2part of Z-hydroxy- 4-methoxy benzophenone, 0.5 part of phenyl salicylateand 0.015 part of mixed alkyl trimethyl ammonium chloride. This mixturehas a viscosity of 4.4 stokes and gives a U. L. bench test burning timeof less than 5 seconds when evaluated as in Example 1.

Mix (b) 65 parts of the brominated polyester base, 26 parts styrene,0.0065 part of hydroquinone, 4.7 parts methyl methacrylate, 4.7 partstriethylphosphate, 0.5 part epichlorohydrin, 0.5 part phenyl salicylate,0.2 part 2-hydroxy-4-methoxy benzophenone, 0.03 part zinc octasol and0.016 part of a mixed alkyl trimethyl ammonium chloride are combined togive a clear very low color copolymerizable mixture having a viscosityof 4.0 stokes. This mixture when cured in inch thick laminates using 1%cumene hydroperoxide and 1% tert-butyl perbenzoate as catalysts andprepared as described in Example 1 gives burning times of less than 2seconds when tested according to the U. L. bench test. The Barcolsurface hardness of these laminates is 45 to 50, indicating good cure.

Mixes (a) and (b) after catalyzing each with 1% cumene hydroperoxide and1% tert-butyl perbenzoate are used to produce approximately 100 linealfeet each of inch thick by 26 inches wide translucent corrugatedbuilding panels on a commercial panel machine. In such machine acontinuous width of fiberglass mat is impregnated with catalyzed resin,encased both sides with cellophane, and pulled through an oven havingtemperature Zones of increasing temperatures up to about 250 F. Duringthe heating period the resin-glass composition is gelled, thecorrugations are formed prior to hard cure and the panels emerge fromthe oven fully cured. The Barcol hardness of both sets of panels thuslyproduced are in the 40 to 50 range and all panels Weigh approximately 10ounces per square foot.

U. L. bench tests performed on specimens from these panels give burningtimes of less than 2 seconds. Full sized tunnel tests performedaccording to ASTM E-84 give flame spread ratings of 75 and respectively,for mix (a) and (b). Similar standard non-fire retardant panels haveflame spread ratings in the range of 300 to 400, with the bestcommercially available fire retardant panel of equal weight being in therange of 50 to 100.

Mix (c) 73.0 parts of the brominated polyester base, 24.2 parts styrene,0.0075 part hydroquinone, 2.8 parts triethyl phosphate, and 0.5 partepichlorohydrin are combined to form a clear, low color, polymerizablemixture having a viscosity of about 27 stokes at 25 C.

Mix (c) is catalyzed with 1% tert-butyl peroctoate and used to moldfiberglass reinforced five gallon capacity wastebaskets in a matchedmetal die heated to about 250 F. The molded translucent products aresubstantially colorless, and have a smooth even surface of approximatelyBarcol hardness. Four ounces of shredded newsprint placed in such basketand ignited, extinguished itself within 3 minutes. Similar baskets madefrom a commercial propylene glycol: isophthalic acid: maleic anhydridepolyester containing enough of the additive tris(2,3- dibromopropyl)phosphate to result in approximately the same bromine and phosphorouscontents require about 9 minutes for the flame to extinguish whenevaluated under the same conditions. The Barcol hardness of the basketsmade with this additive type fire retardant resin is only about 20 to25.

EXAMPLE 4 37.9 percent propylene glycol (equivalent to 1.05 mols), 43.3%tetrahydrophthalic anhydride (equivalent to 0.6 mol), 18.8% maleicanhydride (equivalent to 0.4 mol), and 0.02% hydroquinone, are chargedto a stainless steel vessel equipped for polyesterification reactions.Under a continuous carbon dioxide sparge the ingredients are heated toabout 170 C. at which point the condensa tion reaction starts asevidenced by the removal of Water. The reaction temperature is thenslowly increased to 205 C. and maintained constant to an acid value of98. A further temperature increase to 215 C. is made and maintained atthis temperature until an acid value of 38 and a viscosity of 9 stokesat 25 C. as determined at a 70% concentration in styrene is reached.Heating is discontinued and the polyester base resin is cooled to roomtemperature. The product is a brittle solid having a very low color. 162pounds of this polyester base resin is dissolved in 207 pounds ofmethylene chloride and charged to a 50 gallon glass-lined reactor asdescribed in Example 3.

78 pounds of liquid bromine are added continuously over a 7 hour periodwhile maintaining the reaction temperature at 25 to 33 C. with cooling.On completion of the bromine addition the solvent is distilled out atatmospheric pressure up to 135 C. The brominated base polyester istransferred to separate vessels for cooling. This product contains 32.5%combined bromine and has a Viscosity of about 10 stokes when measured asa solution in styrene at 25 C.

The U. L. bench test applied to laminates prepared from a 67% solutionof this brominated polyester in styrene as described in Example 1 givesburning times of less than 10 seconds.

The results from the Bureau of Ships burning test (Federal Test Standard406Test Method 2023) employing this polyester on 40 ply, /2 inchlaminates prepared as described in Example 2 gives an average ignitiontime of 65 seconds; and average burning time of 71 seconds.

EXAMPLE 5 (a) Preparation of dibromotetrahydrophthalic anhydride To awell stirred slurry of 456 grams (3.0 mols) of 4- cyclohexene 1,2dicarboxylic anhydride (tetrahydro phthalic anhydride) in 900 mls. ofcarbon tetrachloride and mls. of glacial acetic acid are added 480 grams(3.0 mols) of bromine over a period of ten hours at 18 to 25 C. Anadditional 900 mls. of carbontetrachloride are added during this periodto maintain adequate stirring of the fine granular suspension of4,5-dibromocyclohexane 1,2 dicarboxylic anhydride(dibromotetrahydrophthalic anhydride) which forms. The product obtainedafter filtration, washing with toluene, and recrystallization frommethyl ethyl ketone has a melting point of 142 to 144 C. and a brominecontent of 48% compared to 51.3% theoretical.

(b) Preparation of polyester A one-liter resin kettle equipped forpolyesterification reactions is charged with 127 grams (1.67 mols) ofpropylene glycol, 183 grams (0.79 mols) of the dibromotetrahydrophthalicanhydride from (a) and 77.5 grams maleic anhydride (0.79 mols). 0.5%sodium acetate is added as an aid to esterification and the mixture isheated to C. At that point condensation starts and continues for aperiod of 10 hours up to to C. Instead of the calculated 27.5 mls. ofwater the condensate is made up of 47 mls. top layer and 21 mls. bottomlayer. At a plateau acid value of 83, 0.35 mol of additional propyleneglycol is added to compensate for the decomposition losses. The finalacid value is 38 and the resulting polyester has a viscosity in 30% byWeight of styrene of 5 stokes at 25 C. The styrene solution is turbidand has an unsatisfactory medium brown color in excess of 2000 on theAPHA standard. The bromine content of the solid polyester base is only23% compared to the theoretical 29.8% based on the amount ofdibrornotetrahydrophthalic anhydride charged. The bottom layer ofcondensate is found to contain the lost bromine. It is believed that thedibromotetrahydrophthalic anhydride dehydrobrominated at theesterification temperatures employed causing the HBr formed to act onthe propylene glycol as a catalyst in a dicyclization reaction and reactdirectly With propylene glycol to form propylene bromohydrin which woulddistill from the esterification reaction as an azeotrope with water.

Glass reinforced laminates prepared from a 70% concentration in styreneof this bromine containing polyester are subjected to the Globar BurningTest (ASTM D757) 17 and the U. L. Bench Test. The following data areobtained:

Globar test-0.19 inch/min. U. L. bench testNot self-extinguishing.

EXAMPLE 6 10,188 grams (134 mols) of propylene glycol, 4,716 grams (31.9mols) of phthalic anhydride, 14,832 grams (31.9 mols) oftetrabromophthalic anhydride, 6,264 rams (64 mols) of maleic anhydride,and 59 grams of sodium acetate are charged to a 10 gallon stainlesssteel vessel equipped for polyesterification reactions. The mixture isheated to 160 to 170 C. to start the condensation reaction andthereafter is processed at 193 to 194 C. during a period ofapproximately 7 hours to an acid value of 25 and viscosity of 4.9 stokeswhen measured at a 70% concentration in styrene at 25 C. After thereaction is discontinued, 3.4 grams of hydroquinone are added and thebromine containing polyester is transferred to separate vessels andallowed to cool to a light yellow, hazy, brittle solid containing 30.4%bromine.

' 69 parts of the bromine containing polyester are combined with 31parts of styrene to form a copolymerizable mixture having a light yellowcolor, a hazy appearance, a viscosity of 4.0 stokes at 25 C. and abromine content of 21.0%. This mixture is used to prepare both ,4 inchthick laminates and A inch thick 40 ply laminates previously describedin Examples 1 and 2. These laminates were tested for flame resistanceaccording to the U. L. Bench Test and the Bureau of Ships Test (TestMethod 2023). The following data are obtained:

U. L. bench test-FailedNot self-extinguishing Bureau of ShipstestIgnition time-75 sec.; (passes) Extinguishing time135 sec. (fails).

Thus by equating Examples 5 and 6 with previous examples it can readilybe seen, based on a comparison of I fiame retardancy vs. amount ofhalogen used, that the post halogenated polyesters of this inventiongive fire retardancy superior to polyesters prepared from halogenatedcomponents.

EXAMPLE 7 A polyester based on chlorendic anhydride was preparedaccording to the instructions and the proportions of raw materials setforth in Example 1 of US. 2,779,- 701 as follows:

172.6 grams of ethylene glycol (2.78 mols) and 294.2 grams (2.78 mols)of diethylene glycol were charged to a two liter resin kettle equippedfor polyesterification reactions and the mixture was heated to about 100C. 1290 grams of chlorendic anhydride (1,4,5,6,7,7-hexachlorobicyclo(2.2.1) 5 heptene-2,3-dicarboxylic anhydride) (3.48 mols) and 231.4grams of maleic anhydride (2.36 mols) were added and the mixture wasfurther heated to about 155 C. at which point the condensation reactionbegan.

The mixture was reacted at temperatures of 169 to 171 .C. until an acidvalue of 55 was reached. 11.8 grams of tetrahydrofurfuryl alcohol wereadded and the polyester further processed at 171 to 174 C. to an acidvalue of 44. An 1895 gram yield of polyester was obtained having achlorine content of 38.4% and a viscosity of approximately 4.3 stokeswhen measured at a concentration of 70% in styrene at 25 C.

Three separate copolymerizable mixtures of this polyester with varyingconcentrations of styrene were prepared as indicated below. All mixeshad low color but were turbid. Using these mixtures catalyzed with 1% ofbenzoyl peroxide, Ms inch thick 2-ply and V2 inch -ply glass reinforcedlaminates were prepared, cured, and subjected to the HLT-15 burning testand the Bureau of Ships burning test (Method No. 2023.2) as previouslydecribed.

Results are shown in Table I.

TABLE I Burning tests Percent Percent Viscosity, Percent base styrenestokes chlorine HLT-15 Buships Mix resin an-.- 70 a0 4. a 26.8 50 b 8119 360 31. 1 55 c 56. 5 43. 5 0. 5 21. 5 20 l Ignition: 72 see.; Extiug:see. 2 Ignition: 71 see; Exting: 167 see.

Mix (a) is at a viscosity suitable for'practical handling in commercialuse. With mix (b) an attempt was made to achieve maximum chlorinecontent. The viscosity was too heavy to prepare the 40-ply laminate forthe Bureau of Ships Test and also due to the high viscosity only onelayer of glass could be used in the HLT-lS laminate.

The burning tests demonstrate that these chlorinated polyester resinsare inferior at the same halogen content, 1 times the halogen contentand at the same viscosity as halogenated polyester resins prepared bythe method of the present invention.

EXAMPLE 8 (a) Polyester preparation A four-liter resin kettle equippedfor polyesterification as previously described is charged with 764 grams(12.3 mols) ethylene glycol, 808 grams (7.6 mols) diethylene glycol and1588 grams (10.5 mols) tetrahydrophthalic anhydride. The temperature isbrought to C. and kept there for one-half hour, while reaction mixtureis sparged with nitrogen. At this point 840 grams (8.6 mols) maleicanhydride are added and temperature is increased over a 3 hour period to200 to 205 C. and kept at this temperature for another 6 hours. At theend of the reaction 93% of theoretical water is collected. The polyesterhas an acid value of 29.1 and the yield is 91.4%. A 30% styrene solutionhas a color of less than 100 APHA and a viscosity of 6.5 stokes. To thehot resin 0.4 gram of hydroquinone is added and the mass is cooled toroom temperature.

(b) Bromination 2093 grams of the base polyester prepared in (a) aredissolved in 2093 grams of methylene chloride at ambient temperature. Tothis solution are added 935 grams (5.84 mols) of bromine over a periodof 5 hours while maintaining the temperature between 15 to 20 C. Theresulting solution is very pale yellow and clear. Solvent distillationis carried out as before between 42 C. to 143. C. The resultingbrominated polyester base is a very pale colored, brittle solid oncooling, having an acid value of 16, a bromine content of 30.9% and aviscosity of 6 stokes as measured as a 70% concentration in styrene at25 C. HBr recovered from the distilled solvent is 0.27% based on thebrominated polyester. 68 parts of this brominated polyester aredissolved in 32 parts of styrene containing about 0.007 parts ofhydroquinone to form a copolymeriza'ble mixture having a viscosity of4.4 stokes at 25 C. and bromine content of 21%.

(c) Evaluation In the following test flame resistance and physicalstrength of the brominated polyester prepared in (b) are compared to acommercially available polyester-styrene copolymerizable mixturecomprising approximately 1.10 mols ethylene glycol, 0.33 mols maleicanhydride and 0:67 mols of chlorendic anhydride, containingapproximately 27% chlorine and is believed to contain 3 to 5% oftriethylphosphate as a booster flame retardant. Fiberglass reinforcedlaminates for burning tests are prepared as previously described. Thelaminates used for physical strength tests are prepared by impregnatingtwelve layers of Type-181 glass cloth with each of the polyester resinscatalyzed with 1% benzoyl peroxide, pressing the laminates to A; inchstops between platens heated to 200 to 220 F. for 1 hour and furtherpost-curing the laminates in an oven at 300 F. for 2 hours. Theselaminates which contain 65 to 68% glass are tested according toprocedures described in the Bureau of Ships test, (Federal Test StandardNo. 406Test Method No. 2023). Results are givenin Table II.

As can be seen from these data the brominated polyester-containinglaminates are in most instances superior in both flame retardant andphysical strength properties to the commercially availablehalogen-containing polyester.

cobalt octoate. This resin mixture containing approximately 18.2%bromine is catalyzed with 1% methyl ethyl ketone peroxide and used toprepare several /B-lHCh thick glass reinforced laminates comprising twolayers of 2 oz. per square foot glass mat with a 10 mil thick glass matsurface veil on both sides. The laminates are allowed to gel and cure atroom temperature with no elevated temperature postcure.

Similar laminates are prepared from a commercial polyester resin widelyused for fabrication of chemical and corrosion resistant equipment. Thisproduct is composed of a polyester comprising 0.5 mol of chlorendicanhydride, 0.5 mol fumaric anhydride and 1.1 mols propylene glycol, saidpolyester dissolved in styrene to form a copolymerizable mixture. Theproduct as used in industry contains approximately 18% chlorine.

All laminates are checked for flexural strength and Barcol surfacehardness prior to immersion in various corrosive media at varioustemperatures. After threemonth exposure the laminates are removed fromthe test media and retested for flexural strength and Barcol hardness.Results are reported in Table III in percent retention of original testvalues.

TABLE III [Comparison of corrosion resistance of brominated polyester ofExample 9 to commercial chlorendic resin] Percent flex. strength ret.Percent Barcol ret.

Comercial Commercial Test media Temp., F. Ex. 9 resin Ex. 9 resin 10%NaOH 170 52 O 71 0 5% HNO;; 170 97 96 100 90 170 90 85 97 85 Deionizedwater- 170 98 87 91 53 Toluene 75 52 53 8 0 Ethyl gasoline 75 100 100100 75 Wet chlorine 212 35 28 53 31 EXAMPLE 9 To a two-liter resinreaction kettle equipped for polyesterification reactions as previouslydescribed are charged 874 grams (8.4 mols) of neopentyl glycol, 746grams (4.90 mols) of tetrahydrophthalic anhydride, 381 grams (3.29 mols)of fumaric acid, and 0.6 grams of hydroquinone. On application of heatthe polyesterification reaction starts at 175 C. and is continuedthrough seven hours duration at temperatures ranging from 175 C. to 218C. The reaction is discontinued at an acid value of 24 and a viscosityof 4.4 stokes as measured at a 60% concentration in styrene at 25 C. Oncooling, the product is a brittle solid having a very low color.

2200 grams of the polyester base are dissolved in 1800 grams ofmethylene chloride at ambient temperature. To this solution are added962 grams bromine over a 4 /2 hour period while keeping the reactiontemperature below C. with cooling. The removal of the methylene chlorideis carried out in an inert atmosphere over a 5-hour period: up to atemperature of 155 C. The final brominated polyester has a brominecontent of 30.4% and a viscosity of 4.1 stokes when measured at a 60%solution in styrene.

A solution of 60 parts brominated base resin and parts of styrene areprepared to which is added 0,4 part Additional 42-inch thick testlaminates are prepared as previously described and are subjected to theGlobal burning test (ASTM D-757) with the following burning rateresults:

Example 9 Brominated resin-0.09 inch/min. Commercial chlorendicresin-0.39 inch/min.

EXAMPLE 10 Mix A Mix B Polyester base resin 38. 5 39. 0 Styrene 31. 532. O Chlorinated paratfin 30. 0 Tetrakis (2,3-dibromopropy1) silicate29. 0 Chlorine content, percent 21.0 Bromine content, percent One-eighthinch thick fiberglass reinforced laminates were prepared using 2 layersof 2 oz. per square foot glass mat and the resins catalyzed with 1%cumene hydroperoxide and 1% tertbutylperocoate. The panels were curedfor 3 hours at 125 C.

A similar laminate was prepared from a 30% styrene solution of thebrominated polyester base of Example 8.

All laminates were tested for flexural strength, Barcol hardness, andwere subjected to the HLT-15 burning test before and after immersion inboiling water for 12 hours.

HLT15 Flexural strength, p.s.i. Barcol Unboiled Boiled EXAMPLE 11 776grams (12.5 mols) of ethylene glycol, 314 grams (1.3 mols) of 2,2'-bis(phydroxy cyclohexyl)propane, and 1195 grams (7.85 mols) oftetrahydrophthalic anhydride are reacted in a three-liter resin kettleequipped for polyesterification over a period of eight hours at 207 C.maximum temperature to an acid value of 22. After cooling to 140 C., 515grams (5.25 mols) of maleic anhydride are added and the reaction mixtureis processed at approximately 210 C. for six hours. 0.28 gram ofhydroquinone is added and the reaction discontinned. On cooling, thereaction product is a brittle solid having an acid value of 15 and aviscosity of stokes as measured as a 70% solution of the resin instyrene at C.

950 grams of the polyester base resin are dissolved in 1070 grams ofmethylene chloride after which 462 grams of bromine are added over afive-hour period at temperatures ranging from 32 C. to 43 C. On removalof. the methylene chloride by distillation up to 145 C., the finalproduct is a pale yellow very brittle solid having an acid value of 13and a viscosity of 23 stokes when dissolved in by weight of styrene. Thebromine content of the solid is 31.7

-inch laminates prepared from a 30% styrene solution of this brominatedpolyester catalyzed with 0.6% cumene hydroperoxide and 1% benzoylperoxide extinguish in less than 4 seconds when tested according to theU. L. bench test.

EXAMPLE 12 840 grams (13.55 mols) of ethylene glycol and 784 grams (5.15mols) of tetrahyrophthalic anhydride are reacted in a three-literpolyesterification kettle at 160 to 190 C. to an acid value of 14. 5550grams (1.29 mols) of1,2,3,4,9,9-hexachloro-l,4,4a5,6,7,8,8a-octahydro-1,4-methanonaphthalene-6,7-dicraboxylic anhydride, and 626 grams (6.4 mols)of maleic anhydride are added after cooling to 145 C. and the resin isfurther reacted for an additional eight hours at temperatures between160 and 210 C. 0.14 gram of hydroquinone are added and the reaction massis allowed to cool to avery brittle solid having an acid value of 22 anda viscosity of 13 stokes when dissolved in 30% by weight of styrene.

945 grams of the polyester base resin dissolved in 1070 grams ofmethylene chloride are brominated with 295 grams of bromine over aperiod of four hours at temperatures between 33 C. and 41 C.Distillation of methylene chloride is carried out at temperatures up to135 C. to recover a brominated polyester resin which on cooling is abrittle solid containing 23.8% bromine and 8.1% chlorine.

M -inch laminates made from a 70% solution of this brominated base resinin styrene gave a burning time of less than 5 seconds when testedaccording to the bench test.

EXAMPLE 13 To a twio-liter glass estertification kettle are charged 1096grams (7.6 mols) of 1,4-cyclohexane dimethanol and 550 grams (3.6 mols)of tetrabydrophthalic anhydride. The mixture is heated to C. to form ahomogeneous melt and 354 grams of maleic anhydride (3.6 mols) are added.The polyesterification is carried out during a period of about sevenhours at 180 to 209 C. until the acid value decreases to 30 and theviscosity in 35% by weight of styrene is 22 stokes at 25 C. 0.1 gram ofhydroquinone is added and the resin is allowed to cool to a brittlesolid.

227 grams of the polyester base are dissolved in 402 grams of methylenechloride and treated with 72 grams of bromine at temperatures rangingfrom 10 to 18 C. The solvent is removed at temperatures up to C. to forma very light colored brominated polyester having a bromine content of24.1%.

Az-inch laminates prepared as previously described from a solution of65% by weight of this brominated polyester in styrene give burning ratesof 0.16 to 0.18 inch per minute when tested according to the Globar test(ASTM D-757).

EXAMPLE l4 Into athree-liter kettle equipped for polyesterification aspreviously described are placed 1260 grams (7.7 mols) of endic anhydride[endo-cis-bicyclo(2.2.1)-5-heptene-2, 3-dicarboxylic anhydride] and 920grams (14.85 mols) of ethylene glycol. The mixture is heated to 90 C. toform a homogeneous melt and 620 grams (6.33 mols) of maleic anhydrideare added. The reaction mixture is further heated for approximatelyeight hours at temperatures of 180 to 212 C. 0.14 gram of hydroquinoneare added and the base polyester is cooled to room temperature. Thisproduct has an acid value of 22 and a viscosity of 10 stokes whenmeasured at a 70% concentration in styrene.

951 grams of the base polyester are dissolved in 1075 grams of methylenechloride. Using the same equipment as previously described forbromination reactions, 327 grams of bromine are added over a three-hourperiod at 11 to 15 C. As in previous reactions the bromine reacts nearlyinstantaneously to form a very pale yellow solution. The methylenechloride is evaporated over a threehour period at tempreatures up to C.The brominated polyester is then cooled to 105 C., treated with 0.13gram of hydroquinone and dissolved in styrene to a concentration of 74%.This solution has a viscosity of 6.2 stokes at 25 C. The bromine contentof the brominated base polyester is 25.2%.

A -inch thick laminates prepared from this styrene solution (brominecontent=18.2%) catalyzed with 0.6% cumene hydroperoxide and 1% benzoylperoxide, and cured for three hours at 180 B, have a -Barcol hardness of50 indicating good cure. The U.L. bench test performed on theselaminates gives extinguishing times of less than 6 seconds after removalof the flame.

EXAMPLE 15 To a four-liter resin kettle equipped for polyesterificationreactions are charged 965 grams (11.0 mols) of 2- butene-1,4-diol, 555grams (9.1 mols) of ethylene glycol, and 1370 grams (9.3 mols) ofphthalic anhydride. The mixture is heated to 90 C. to form a homogeneousmelt and 910 grams (9.3 mols) of maleic anhydride are added. Theexterification is carried out over and extended period at temperaturesheld to 130 to C. due to the tendency of the butene diol to cyclize anddistill out together with the normal Water of condensation. During thereaction the amount of butene diol loss is determined from the amount ofthe cyclization product, 3-dihydrofuran, found in the distillate and isreplaced in the reac- 23 tion mixture with fresh 2-butene-1,4-diol. Thereaction is discontinued at an acid value of 57 and a viscosity of 25stokes when measured at a 70% concentration of base polyester in styreneat 25 C.

951 grams of the base polyester resin are dissolved in 951 grams ofmethylene chloride. To this solution are added over a seven-hour period464 grams of bromine at temperatures of 5 to C. The bromine is absorbedreadily as in prior examples to form a clear pale yellow solution. Themethylene chloride is evaporated as before over a 3% hour period attemperatures up to 136 C. to recover a brominated polyester which, oncooling, is a brittle solid having a bromide content of 32.7% and aviscosity of 9 stokes when measured as a solution in 34% by weight ofstyrene at 25 C.

Laminates suitable for the Globar burning test (ASTM D757) and the U.L.bench test are prepared from a 34% by weight styrene solution of thisbrominated polyester with conventional catalysts and curing cycles aspreviously described. Barcol surfaces hardness is 45 to 50. Buring testson these laminates have the following results:

U.L. Bench Test-0.07 inch/min. Globar Test-Extininguishing time lessthan 5 seconds.

EXAMPLE 16 400 grams of the base polyester of Example 1(a) are dissolvedin 400 grams of methylene chloride. To this solution, maintained at atemperature between 5 C. and 14 C. by cooling, are added below theliquid surface 81 grams of chlorine gas over a period of about fourhours. The reaction is near instantaneous as with bromine. The methylenechloride is removed by distillation at temperatures up to 155 C. torecover a chlorinated polyester which when cooled is a brittle solidhaving a chlorine content of 16%. A 65% by 'weight concentration of thechlorinated base resin in styrene has a viscosity of stokes at 25 C. anda color of less than 200 APHA. Laminates prepared as previouslydescribed are cured without difliculty and exhibit a Globar (ASTM D-757)burning rate of 0.31 inch/min.

EXAMPLE 17 In polyesterification equipment as previously described 1347grams (17.7 mols) of propylene glycol are reacted with 1653 grams (16.9mols) of maleic anhydride at temperatures up to 210 C. until an acidvalue of 27 is reached.

801 grams of this base polyester resin are dissolved in 900 grams ofmethylene chloride and 545 grams of bromine are added over a 24-hourperiod at 40 to 43 C. The addition of bromine to the maleic moiety takesplace 'with difiiculty as evidenced by a color of excess ibrominepresent at all times and the generation of significantly greater thannormal amounts of hydrogen bromide. The amount of bromine added isequivalent to approximately two thirds of the unsaturation present thustheoretically leaving one third free to copolymerize later with styrene.After removal of the methylene chloride the resultant brominatedpolyester is a light brown brittle solid having a bromine content of41.4%, an acid value of 83, and a viscosity at a 7 0% concentration instyrene of 8 stokes at 25 C.

Attempts to prepare laminates for burning tests from the styrenesolution using conventional catalysts are unsuccessful, i.e., themixture will gel but no Barcol reading is obtained even on prolongedheating.

This example demonstrates that while bromination does take place withdifliculty in the absence of non-alpha, beta-ethylenic unsaturationsatisfactory curable polyester products are not obtatined.

EXAMPLE 18 A hydroxyl rich polyester was prepared by reacting 2280 grams(17.2 mols) of trimethylol propane with 24 1220 grams (8.0 mols) oftetrahydrophthalic anhydride in a 4-liter reaction kettle equipped forpolyesterification reactions. The mixture was reacted over a period of 8hours at temperatures of 155 C. to 195 C. to an acid value of 12. Oncooling, the resulting tetrafunctional polyol had a viscosity of 200stokes at 25 C.

2284 grams of this base polyester were dissolved in 1760 grams ofmethylene chloride and treated with 830 grams of bromine over a 3% hourperiod at 14 C. The resulting brominated polyol after removal of thesolvent was a clear very light colored semisolid having an acid value of4, a Ibromine content of 27%, and a hydroxyl equivalent of 125.

An isocyanate rich prepolymer was prepared by reacting 800 grams oftolylene diisocyanate with 200 grams of the brominated polyol at aboutC. The prepolymer, to which was added 0.5% of 2,6-ditertiary butyl-4-methyl phenol as an antioxidant, had a viscosity of 6 stokes at 25 C.,an amine equivalent of 132 and an excess NCO content of 31.9%.

In order to reduce the viscosity of the brominated polyol so that itcould be combined with the prepolymer, 72 parts of brominated polyolwere blended with 28 parts of diethylene glycol to form a polyol mixturehaving a viscosity of about stokes at 25 C. and a hydroxyl equivalent of87.

A foam was then prepared by combining 62.3% prepolymer, 35.5% of thediethylene glycol modified polyol, 0.6% water, 0.1% N-ethyl morpholine,1.09 DC-113 (a proprietary silicone surfactant manufactured by the DowCorning Corp.) and 0.5% of Surfactol 365 (a proprietary castor oil basedsurfactant manufactured by the Baker Castor Oil Co.). The cream time ofthis for mulation was 1.5 minutes and the foam was fully risen after 6minutes to a rigid structure having a density of 3.5 lbs/"cu. ft.

Specimens cut from this foam were very slow burning toself-extinguishing when tested according to ASTM D-1692. In this test a-inch thick by 2-inch by 6-inch foam specimen is supported horizontally,fiatwise on a piece of hardware cloth. A bunsen Iburner with a wing topis placed under one end of the specimen for a duration of one minute. Onremoval of the flame the burning rate and/ or self-extinguishingcharacteristics are observed.

EXAMPLE 19 To a 3 liter kettle equipped for polyesterification werecharged 835 grams (13.5 mols) of ethylene glycol, 972. grams (9.9 mols)of maleic anhydride, 472 grams (3.3 mols) of phthalic anhydride and 699grams (5.3 mols) of bicyclopentadiene. The mixture was heated to 128 142C. and kept at this temperature for 3 hours. The temperature was thenslowly increased to C. and kept there for another 13 hours until theacid value was 27 and the viscosity 5.5 stokes as measured at 70%concentration in styrene at 25 C. About 50 cc. (48 g.) of unreactedbicyclopentadiene were collected during the reaction together with thewater of condensation. Actual amount of bicyclopentadiene having reactedthus was 651 g.

1499 grams of the above base polyester were dissolved in an equal weightof methylene chloride. Using the bromination equipment previouslydescribed, 560 grams of bromine were added to the well stirred solutionover a period of 6 hours keeping the temperature between 710 C. Thebromine reacted immediately. The methylene chloride was evaporated overa 5 hour period by increasing the batch temperature to 133 C. The hotpolyester was dissolved in styrene to a final concentration of 74.4%.This solution had a viscosity of 9.0 stokes. The brominated polyesterbase had an acid value of 29.0, and a bromine content of 27.2%.

-inch thick glass reinforced laminates prepared from the above styrenesolution (bromine content 20.8%)

catalyzed with 0.7% cumene hydroperoxide and 0.5% benzoyl peroxide paste(50% active) and cured for 3 hours, had a Barcol hardness of 50. TheU.L. bench test on these laminates gave burning times of less than 5seconds after removal of the flame.

Globar (ASTM D-757) laminates of A5" thickness were prepared andcatalyzed as above. The Barcol hardness of these laminates was 50 andthe average burning rate was 0.07 inch/min.

EXAMPLE 20 1119 grams of diethylene glycol (10.5 mols) and 258 grams ofglyceryl alpha allyl ether (1.95 mols) were reacted with 921 grams oftetrahydrophthalic anhydride (6.06 mols) and 702 grams of fumaric acid(6.06 mols) in a reaction vessel equipped with inert gas inlet, stirrer,thermometer and distilling column. After 6 hours at temperatures of 160C. to 205 C. a clear light colored polyester was obtainedhaving an acidvalue of 35 and a viscosity at 25 C., of 3.7 stokes in 35% styrene. 300grams of the polyester thus prepared were readily dissolved in 300 gramsof methylene chloride. 140 grams of bromine, equivalent to 97.5% oftheoretical amount, based on the combined tetrahydrophthalic anhydrideand glyceryl alpha allyl ether present were added to this solution overa 45 minute interval, at temperatures of 15 to 25 C.

After removal of methylene chloride by distillation, at batchtemperatures from 50 to 165 C., a light colored, clear polyester wasobtained which contained 31.8% bromine.

Infrared analysis of polyester samples taken at various stages duringthe bromination reaction indicated that the rate of disappearance of theallyl unsaturation and that of the tetrahydrophthalic unsaturation areapproximately equal while the alpha,beta ethylenic unsaturation derivedfrom the fumaric acid was not disturbed.

We claim:

1. A halogenated polyester comprising the reaction product of (1) ahalogen selected from the group consisting of chlorine, bromine andmixtures thereof with (2) a polyester which is the product of thereaction of at least one alpha, beta-ethylenically unsaturateddicarboxylic acid or anhydride containing up to about 20 carbon atomsper molecule and at least one compound containing aliphatic unsaturationhaving a halogenation rate faster than that of the alpha,beta-ethylenically unsaturated dicarboxylic acid or anhydride selectedfrom the group consisting of (A) polyhydric alcohols having about 2 to24 carbon atoms containing active unsaturation which is subject tosubsequent halogenation and (B) a mixture of at least one polyhydricalcohol having about 2 to 24 carbon atoms and at least one ethylenicallyunsaturated dicarboxylic acid or anhydride containing up to about 20carbon atoms free of any alpha, beta-ethylenic unsaturation other thanaromatic unsaturation; substantially all of the alpha, beta-ethylenicunsaturation remaining unreacted with the halogen and available forsubsequent polymerization with a cross-linking agent; the alpha,beta-ethylenically unsaturated dicarboxylic acid or anhydride comprisingabout 15 to 67 mol percent of the polyester; the halogen comprisingabout to 50 percent by weight of the halogenated polyester.

2. The halogenated polyester of claim 1 wherein the compound containingaliphatic unsaturation having a halogenation rate faster than that ofthe alpha, betaethylenically unsaturated dicarboxylic acid or anhydrideis a polyhydric alcohol containing about 2 to 24 carbon atoms.

3. A cross-linked halogenated polyester which is the reaction product of(1) the halogenated polyester of claim 1; and (2) approximately 20% to60% by weight based on the weight of the polyester of a polymerizableethylenically unsaturated monomer containing a 26 CHFC group.

4. A halogenated fire-retardant polyester comprising the reactionproduct of (1) a polyester which is the prod net of the reaction of (a)an alpha, beta-ethylenic unsaturated dicarboxylic acid or anhydridecontaining up to about 20 carbon atoms per molecule; (b) anethylenically unsaturated dicarboxylic acid or anhydride containing upto about 20 carbon atoms per molecule free of any alpha, beta-ethylenicunsaturation other than aromatic unsaturation other than aromaticunsaturation and (c) a polyhydric alcohol containing about 2 to 24carbon atoms; and (2) a halogen selected from the group consisting ofchlorine and bromine; substantially all of the alpha, beta-ethylenicunsaturation remaining unreacted with the halogen; the amount of (a)comprising about 15 to about 67 mol percent of the polyester; the amountof b) 'being sufficient to result in a halogenated polyester having ahalogen content of about 10% to 50% by weight of the halogenatedpolyester; the amount of (c) being about to of the amount theoreticallynecessary to react with all. of the carboxylic groups present; theamount of halogen being approximately that theoretically required toreact with the nonalpha, beta ethylenic unsaturation of b).

5. The halogenated fire-retardant polyester of claim 4 wherein thealpha, beta-ethylenic unsaturated dicarboxylic acid or anhydride isselected from the group consisting of maleic acid or anhydride andfumaric acid.

6. The halogenated fire-retardant polyester of claim 4 wherein theethylenically unsaturated dicarboxylic acid or anhydride free of anyalpha, beta ethylenic unsaturation other than aromatic unsaturation istetrahydrophthalic acid or anhydride.

7. The method of preparing a halogenated polyester composition whichcomprises the steps of:

(1) mixing at least one alpha, beta-ethylenically unsaturateddicarboxylic acid or anhydride containing up to about 20 carbon atomsand at least one compound containing aliphatic unsaturation having ahalogenation rate faster than that of the alpha, betaethylenicallyunsaturated dicarboxylic acid or anhydride, said compound being selectedfrom the group consisting of (A) polyhydric alcohols having about 2 to24 carbon atoms containing active unsaturation which is subject tosubsequent halogenation and ('B) a mixture of at least one polyhydricalcohol having about 2 to 24 carbon atoms and at least one ethylenicallyunsaturated dicarboxylic acid or anhydride containing up to about 20carbon atoms free of any alpha, beta-ethylenic unsaturation other thanaromatic unsaturation, the alpha, beta-ethylenically unsaturateddicarboxylic acid or anhydride comprising about 15 to 67 mol percent ofthe mixture;

(2) heating the mixture to a temperature in the range of to 250 untilesterification is complete;

(3) recovering the polyester thus produced;

(4) dissolving the polyester in a solvent which is not readilysusceptible to halogenation;

(5) introducing a halogen selected from the group 'consisting ofchlorine and bromine in an amount approximately equal to thattheoretically required to react with the said aliphatic unsaturation andsuflicient to produce a halogenated polyester containing approximately10 percent to 60 percent by weight of halogen;

(6) maintaining the reaction mixture at a temperature in the range ofabout 50 C. to about 50 C. until the desired degree of addition ofhalogen to the aliphatic unsaturation of the polyester is achieved;substantially all of the alpha, beta-ethylenic unsaturation remainingunreacted with the halogen;

(7) removing the solvent at a temperature below 180 C.; and

(8) recovering the desired halogenated polyester composition.

8. The method of claim 7 wherein the amount of polyhydric alcohol isbetween an amount suflicient to react theoretically with all of thecarboxyl groups present and 125 percent of such theoretical amount.

9. The method of claim 7 wherein the halogen is bromine.

10. The method of preparing a cross-linked halogenated polyester whichcomprises the steps of:

(1) preparing a halogenated polyester composition by the method of claim7;

(2) mixing said halogenated polyester With approximately 20% to 60% byweight based on the weight of the polyester 01: an ethylenicallyunsaturated monomer having a CH C group and being capable ofcopolymerization with the alpha, betaethylenic unsaturation present inthe polyester; and

(3) polymerizing the mixture.

11. The method of claim 10 wherein the ethylenically unsaturated monomeris styrene.

28 References Cited UNITED STATES PATENTS 3,151,183 9/1964 Bill et al.260-869 3,196,190 7/1965 Nischk et a1. 260-869 2,829,070 4/ 1958 Osborn117-93 3,004,003 10/1961 Batzer 260-861 3,333,022 7/ 1967 Reiners et al.260-869 FOREIGN PATENTS 842,958 9/1958 Great Britain.

OTHER REFERENCES Batzer et al., Diels-Alder Synthesis of UnsaturatedPolyesters, Die Makrumole Kulare Chemie, vol. 44-47, 1961, pp. 179, 188,192.

WILLIAM SHORT, Primary Examiner MELVIN GOLDSTEIN, Assistant Examiner US.Cl. X.R.

